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KN
14 tháng 2 2020
We have two cases:
+) If \(x\ge2016\)then \(x-2016\ge0\Rightarrow\left|x-2016\right|=x-2016\)
Equation becomes: \(x-2016=2016x\)
\(\Leftrightarrow2015x=-2016\Leftrightarrow x=\frac{-2016}{2015}\)(not satisfied)
+) If \(x< 2016\)then \(x-2016< 0\Rightarrow\left|x-2016\right|=2016-x\)
Equation becomes: \(2016-x=2016x\)
\(\Leftrightarrow2017x=2016\Leftrightarrow x=\frac{2016}{2017}\)(satisfied)
So \(x=\frac{2016}{2017}\)
NV
0
GL
2
GL
1
11 tháng 1 2017
Ta có: \(\left(xy+2016z\right)\left(yz+2016z\right)\left(zx+2016y\right)\\ =\left(xy+\left(x+y+z\right)z\right)\left(yz+\left(x+y+z\right)x\right)\left(zx+\left(x+y+z\right)y\right)\\ =\left(xy+zx+zy+z^2\right)\left(yz+x^2+xy+xz\right)\left(zx+xỹ+y^2+yz\right)\\ =\left(y+z\right)\left(x+z\right)\left(x+z\right)\left(y+x\right)\left(z+y\right)\left(x+y\right)\\ =\left(y+z\right)^2\left(x+y\right)^2\left(z+x\right)^2\\ \Rightarrow\frac{\left(xy+2016z\right)\left(yz+2016z\right)\left(zx+2016y\right)}{\left(x+y\right)^2\left(y+z\right)^2\left(z+x\right)^2}\\ =\frac{\left(y+z\right)^2\left(x+y\right)^2\left(z+x\right)^2}{\left(x+y\right)^2\left(y+z\right)^2\left(z+x\right)^2}\\ =1\)
ST
0
TT
1
KN
20 tháng 10 2019
\(x^4+2016x^2+2017x+2016\)
\(=x^4+2016x^2+2016x+x+2016\)
\(=\left(x^4+x\right)+\left(2016x^2+2016x+2016\right)\)
\(=x\left(x^3+1\right)+2016\left(x^2+x+1\right)\)
\(=x\left(x+1\right)\left(x^2+x+1\right)+2016\left(x^2+x+1\right)\)
\(=\left(x^2+x+1\right)\left(x^2+x+2016\right)\)
ĐK: x>0.
Pt\(\left[{}\begin{matrix}x-2016=2016x\\x-2016=-2016x\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=\frac{-2015}{2016}\left(l\right)\\x=\frac{2016}{2017}\end{matrix}\right.\)
Vậy \(S=\left\{\frac{2016}{2017}\right\}\)
Ta có: \(\left|x-2016\right|=2016x\)
\(\Leftrightarrow\left[{}\begin{matrix}x-2016=2016x\\x-2016=-2016x\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x-2016-2016x=0\\x-2016+2016x=0\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}-2015x=2016\\2017x=2016\end{matrix}\right.\)\(\Leftrightarrow\left[{}\begin{matrix}x=\frac{-2016}{2015}\\x=\frac{2016}{2017}\end{matrix}\right.\)
Vậy: \(x\in\left\{-\frac{2016}{2015};\frac{2016}{2017}\right\}\)